avilib.c

mediastreamer2是开源的网络传输媒体流的库

         {
            lseek(AVI->fdes,4,SEEK_CUR);
            continue;
         }

         /* Check if we got a tag ##db, ##dc or ##wb */
	 
         if( ( (data[2]=='d' || data[2]=='D') &&
               (data[3]=='b' || data[3]=='B' || data[3]=='c' || data[3]=='C') )
	     || ( (data[2]=='w' || data[2]=='W') &&
		  (data[3]=='b' || data[3]=='B') ) )
	   {
	   avi_add_index_entry(AVI,(unsigned char *) data,0,lseek(AVI->fdes,0,SEEK_CUR)-8,n);
         }
	 
         lseek(AVI->fdes,PAD_EVEN(n),SEEK_CUR);
      }
      idx_type = 1;
   }

   /* Now generate the video index and audio index arrays */

   nvi = 0;
   for(j=0; j<AVI->anum; ++j) nai[j] = 0;

   for(i=0;i<AVI->n_idx;i++) {
     
     if(strncasecmp((char *)AVI->idx[i],(char *) AVI->video_tag,3) == 0) nvi++;
     
     for(j=0; j<AVI->anum; ++j) if(strncasecmp((char *)AVI->idx[i], AVI->track[j].audio_tag,4) == 0) nai[j]++;
   }
   
   AVI->video_frames = nvi;
   for(j=0; j<AVI->anum; ++j) AVI->track[j].audio_chunks = nai[j];

//   fprintf(stderr, "chunks = %ld %d %s\n", AVI->track[0].audio_chunks, AVI->anum, AVI->track[0].audio_tag);

   if(AVI->video_frames==0) ERR_EXIT(AVI_ERR_NO_VIDS);
   AVI->video_index = (video_index_entry *) malloc(nvi*sizeof(video_index_entry));
   if(AVI->video_index==0) ERR_EXIT(AVI_ERR_NO_MEM);
   
   for(j=0; j<AVI->anum; ++j) {
       if(AVI->track[j].audio_chunks) {
	   AVI->track[j].audio_index = (audio_index_entry *) malloc(nai[j]*sizeof(audio_index_entry));
	   if(AVI->track[j].audio_index==0) ERR_EXIT(AVI_ERR_NO_MEM);
       }
   }   
   
   nvi = 0;
   for(j=0; j<AVI->anum; ++j) nai[j] = tot[j] = 0;
   
   ioff = idx_type == 1 ? 8 : AVI->movi_start+4;
   
   for(i=0;i<AVI->n_idx;i++) {

     //video
     if(strncasecmp((char *)AVI->idx[i],(char *)AVI->video_tag,3) == 0) {
       AVI->video_index[nvi].key = str2ulong(AVI->idx[i]+ 4);
       AVI->video_index[nvi].pos = str2ulong(AVI->idx[i]+ 8)+ioff;
       AVI->video_index[nvi].len = str2ulong(AVI->idx[i]+12);
       nvi++;
     }
     
     //audio
     for(j=0; j<AVI->anum; ++j) {
	 
       if(strncasecmp((char *)AVI->idx[i],AVI->track[j].audio_tag,4) == 0) {
	 AVI->track[j].audio_index[nai[j]].pos = str2ulong(AVI->idx[i]+ 8)+ioff;
	 AVI->track[j].audio_index[nai[j]].len = str2ulong(AVI->idx[i]+12);
	 AVI->track[j].audio_index[nai[j]].tot = tot[j];
	 tot[j] += AVI->track[j].audio_index[nai[j]].len;
	 nai[j]++;
       }
     }
   }
   
   
   for(j=0; j<AVI->anum; ++j) AVI->track[j].audio_bytes = tot[j];
   
   /* Reposition the file */
   
   lseek(AVI->fdes,AVI->movi_start,SEEK_SET);
   AVI->video_pos = 0;

   return(0);
}

long AVI_video_frames(avi_t *AVI)
{
   return AVI->video_frames;
}
int  AVI_video_width(avi_t *AVI)
{
   return AVI->width;
}
int  AVI_video_height(avi_t *AVI)
{
   return AVI->height;
}
double AVI_frame_rate(avi_t *AVI)
{
   return AVI->fps;
}
char* AVI_video_compressor(avi_t *AVI)
{
   return AVI->compressor2;
}

long AVI_max_video_chunk(avi_t *AVI)
{
   return AVI->max_len; 
}

int AVI_audio_tracks(avi_t *AVI)
{
    return(AVI->anum);
}

int AVI_audio_channels(avi_t *AVI)
{
   return AVI->track[AVI->aptr].a_chans;
}

long AVI_audio_mp3rate(avi_t *AVI)
{
   return AVI->track[AVI->aptr].mp3rate;
}

int AVI_audio_bits(avi_t *AVI)
{
   return AVI->track[AVI->aptr].a_bits;
}

int AVI_audio_format(avi_t *AVI)
{
   return AVI->track[AVI->aptr].a_fmt;
}

long AVI_audio_rate(avi_t *AVI)
{
   return AVI->track[AVI->aptr].a_rate;
}

long AVI_audio_bytes(avi_t *AVI)
{
   return AVI->track[AVI->aptr].audio_bytes;
}

long AVI_audio_chunks(avi_t *AVI)
{
   return AVI->track[AVI->aptr].audio_chunks;
}

long AVI_audio_codech_offset(avi_t *AVI)
{
   return AVI->track[AVI->aptr].a_codech_off;
}

long AVI_audio_codecf_offset(avi_t *AVI)
{
   return AVI->track[AVI->aptr].a_codecf_off;
}

long  AVI_video_codech_offset(avi_t *AVI)
{
    return AVI->v_codech_off;
}

long  AVI_video_codecf_offset(avi_t *AVI)
{
    return AVI->v_codecf_off;
}

long AVI_frame_size(avi_t *AVI, long frame)
{
   if(AVI->mode==AVI_MODE_WRITE) { AVI_errno = AVI_ERR_NOT_PERM; return -1; }
   if(!AVI->video_index)         { AVI_errno = AVI_ERR_NO_IDX;   return -1; }

   if(frame < 0 || frame >= AVI->video_frames) return 0;
   return(AVI->video_index[frame].len);
}

long AVI_audio_size(avi_t *AVI, long frame)
{
  if(AVI->mode==AVI_MODE_WRITE) { AVI_errno = AVI_ERR_NOT_PERM; return -1; }
  if(!AVI->track[AVI->aptr].audio_index)         { AVI_errno = AVI_ERR_NO_IDX;   return -1; }
  
  if(frame < 0 || frame >= AVI->track[AVI->aptr].audio_chunks) return 0;
  return(AVI->track[AVI->aptr].audio_index[frame].len);
}

long AVI_get_video_position(avi_t *AVI, long frame)
{
   if(AVI->mode==AVI_MODE_WRITE) { AVI_errno = AVI_ERR_NOT_PERM; return -1; }
   if(!AVI->video_index)         { AVI_errno = AVI_ERR_NO_IDX;   return -1; }

   if(frame < 0 || frame >= AVI->video_frames) return 0;
   return(AVI->video_index[frame].pos);
}


int AVI_seek_start(avi_t *AVI)
{
   if(AVI->mode==AVI_MODE_WRITE) { AVI_errno = AVI_ERR_NOT_PERM; return -1; }

   lseek(AVI->fdes,AVI->movi_start,SEEK_SET);
   AVI->video_pos = 0;
   return 0;
}

int AVI_set_video_position(avi_t *AVI, long frame)
{
   if(AVI->mode==AVI_MODE_WRITE) { AVI_errno = AVI_ERR_NOT_PERM; return -1; }
   if(!AVI->video_index)         { AVI_errno = AVI_ERR_NO_IDX;   return -1; }

   if (frame < 0 ) frame = 0;
   AVI->video_pos = frame;
   return 0;
}

int AVI_set_audio_bitrate(avi_t *AVI, long bitrate)
{
   if(AVI->mode==AVI_MODE_READ) { AVI_errno = AVI_ERR_NOT_PERM; return -1; }

   AVI->track[AVI->aptr].mp3rate = bitrate;
   return 0;
}
      

long AVI_read_frame(avi_t *AVI, char *vidbuf, int *keyframe)
{
   long n;

   if(AVI->mode==AVI_MODE_WRITE) { AVI_errno = AVI_ERR_NOT_PERM; return -1; }
   if(!AVI->video_index)         { AVI_errno = AVI_ERR_NO_IDX;   return -1; }

   if(AVI->video_pos < 0 || AVI->video_pos >= AVI->video_frames) return -1;
   n = AVI->video_index[AVI->video_pos].len;

   *keyframe = (AVI->video_index[AVI->video_pos].key==0x10) ? 1:0;

   lseek(AVI->fdes, AVI->video_index[AVI->video_pos].pos, SEEK_SET);

   if (avi_read(AVI->fdes,vidbuf,n) != n)
   {
      AVI_errno = AVI_ERR_READ;
      return -1;
   }

   AVI->video_pos++;

   return n;
}

int AVI_set_audio_position(avi_t *AVI, long byte)
{
   long n0, n1, n;

   if(AVI->mode==AVI_MODE_WRITE) { AVI_errno = AVI_ERR_NOT_PERM; return -1; }
   if(!AVI->track[AVI->aptr].audio_index)         { AVI_errno = AVI_ERR_NO_IDX;   return -1; }

   if(byte < 0) byte = 0;

   /* Binary search in the audio chunks */

   n0 = 0;
   n1 = AVI->track[AVI->aptr].audio_chunks;

   while(n0<n1-1)
   {
      n = (n0+n1)/2;
      if(AVI->track[AVI->aptr].audio_index[n].tot>byte)
         n1 = n;
      else
         n0 = n;
   }

   AVI->track[AVI->aptr].audio_posc = n0;
   AVI->track[AVI->aptr].audio_posb = byte - AVI->track[AVI->aptr].audio_index[n0].tot;

   return 0;
}

long AVI_read_audio(avi_t *AVI, char *audbuf, long bytes)
{
   long nr, pos, left, todo;

   if(AVI->mode==AVI_MODE_WRITE) { AVI_errno = AVI_ERR_NOT_PERM; return -1; }
   if(!AVI->track[AVI->aptr].audio_index)         { AVI_errno = AVI_ERR_NO_IDX;   return -1; }

   nr = 0; /* total number of bytes read */

   while(bytes>0)
   {
      left = AVI->track[AVI->aptr].audio_index[AVI->track[AVI->aptr].audio_posc].len - AVI->track[AVI->aptr].audio_posb;
      if(left==0)
      {
         if(AVI->track[AVI->aptr].audio_posc>=AVI->track[AVI->aptr].audio_chunks-1) return nr;
         AVI->track[AVI->aptr].audio_posc++;
         AVI->track[AVI->aptr].audio_posb = 0;
         continue;
      }
      if(bytes<left)
         todo = bytes;
      else
         todo = left;
      pos = AVI->track[AVI->aptr].audio_index[AVI->track[AVI->aptr].audio_posc].pos + AVI->track[AVI->aptr].audio_posb;
      lseek(AVI->fdes, pos, SEEK_SET);
      if (avi_read(AVI->fdes,audbuf+nr,todo) != todo)
      {
         AVI_errno = AVI_ERR_READ;
         return -1;
      }
      bytes -= todo;
      nr    += todo;
      AVI->track[AVI->aptr].audio_posb += todo;
   }

   return nr;
}

/* AVI_read_data: Special routine for reading the next audio or video chunk
                  without having an index of the file. */

int AVI_read_data(avi_t *AVI, char *vidbuf, long max_vidbuf,
                              char *audbuf, long max_audbuf,
                              long *len)
{

/*
 * Return codes:
 *
 *    1 = video data read
 *    2 = audio data read
 *    0 = reached EOF
 *   -1 = video buffer too small
 *   -2 = audio buffer too small
 */

   int n;
   char data[8];
 
   if(AVI->mode==AVI_MODE_WRITE) return 0;

   while(1)
   {
      /* Read tag and length */

      if( avi_read(AVI->fdes,data,8) != 8 ) return 0;

      /* if we got a list tag, ignore it */

      if(strncasecmp(data,"LIST",4) == 0)
      {
         lseek(AVI->fdes,4,SEEK_CUR);
         continue;
      }

      n = PAD_EVEN(str2ulong((unsigned char *)data+4));

      if(strncasecmp(data,AVI->video_tag,3) == 0)
      {
         *len = n;
         AVI->video_pos++;
         if(n>max_vidbuf)
         {
            lseek(AVI->fdes,n,SEEK_CUR);
            return -1;
         }
         if(avi_read(AVI->fdes,vidbuf,n) != n ) return 0;
         return 1;
      }
      else if(strncasecmp(data,AVI->track[AVI->aptr].audio_tag,4) == 0)
      {
         *len = n;
         if(n>max_audbuf)
         {
            lseek(AVI->fdes,n,SEEK_CUR);
            return -2;
         }
         if(avi_read(AVI->fdes,audbuf,n) != n ) return 0;
         return 2;
         break;
      }
      else
         if(lseek(AVI->fdes,n,SEEK_CUR)<0)  return 0;
   }
}

/* AVI_print_error: Print most recent error (similar to perror) */

char *(avi_errors[]) =
{
  /*  0 */ "avilib - No Error",
  /*  1 */ "avilib - AVI file size limit reached",
  /*  2 */ "avilib - Error opening AVI file",
  /*  3 */ "avilib - Error reading from AVI file",
  /*  4 */ "avilib - Error writing to AVI file",
  /*  5 */ "avilib - Error writing index (file may still be useable)",
  /*  6 */ "avilib - Error closing AVI file",
  /*  7 */ "avilib - Operation (read/write) not permitted",
  /*  8 */ "avilib - Out of memory (malloc failed)",
  /*  9 */ "avilib - Not an AVI file",
  /* 10 */ "avilib - AVI file has no header list (corrupted?)",
  /* 11 */ "avilib - AVI file has no MOVI list (corrupted?)",
  /* 12 */ "avilib - AVI file has no video data",
  /* 13 */ "avilib - operation needs an index",
  /* 14 */ "avilib - Unkown Error"
};
static int num_avi_errors = sizeof(avi_errors)/sizeof(char*);

static char error_string[4096];

void AVI_print_error(char *str)
{
   int aerrno;

   aerrno = (AVI_errno>=0 && AVI_errno<num_avi_errors) ? AVI_errno : num_avi_errors-1;

   fprintf(stderr,"%s: %s\n",str,avi_errors[aerrno]);

   /* for the following errors, perror should report a more detailed reason: */

   if(AVI_errno == AVI_ERR_OPEN ||
      AVI_errno == AVI_ERR_READ ||
      AVI_errno == AVI_ERR_WRITE ||
      AVI_errno == AVI_ERR_WRITE_INDEX ||
      AVI_errno == AVI_ERR_CLOSE )
   {
      perror("REASON");
   }
}

char *AVI_strerror()
{
   int aerrno;

   aerrno = (AVI_errno>=0 && AVI_errno<num_avi_errors) ? AVI_errno : num_avi_errors-1;

   if(AVI_errno == AVI_ERR_OPEN ||
      AVI_errno == AVI_ERR_READ ||
      AVI_errno == AVI_ERR_WRITE ||
      AVI_errno == AVI_ERR_WRITE_INDEX ||
      AVI_errno == AVI_ERR_CLOSE )
   {
      sprintf(error_string,"%s - %s",avi_errors[aerrno],strerror(errno));
      return error_string;
   }
   else
   {
      return avi_errors[aerrno];
   }
}

uint64_t AVI_max_size()
{
  return((uint64_t) AVI_MAX_LEN);
}